Incorrect SSL certificate validation in Nagios Fusion 4.1.8 and earlier allows for Escalation of Privileges or Code Execution as root via vectors related to download of an untrusted update package in upgrade_to_latest.sh.
https://www.nagios.com/downloads/nagios-xi/change-log/
https://skylightcyber.com/2021/05/20/13-nagios-vulnerabilities-7-will-shock-you/